The City of Los Angeles has completed a four-mile, earthquake-resistant pipeline as part of the Foothill Trunk Line Project, according to announcements made by Mayor Karen Bass and the Los Angeles Department of Water and Power (LADWP) in August 2026. The infrastructure upgrade, which spans parts of Council District 7, is designed to protect the local water distribution network against seismic risks and secure water supplies for emergency responders.
Project Scope and Engineering Specifications
Originally built in the 1930s, the aging pipeline infrastructure previously ranged from 24 to 36 inches in diameter, according to LADWP data. Crews replaced the legacy system with a new 54-inch-diameter pipeline utilizing welded steel pipe and ductile iron pipe equipped with flexible joints designed to withstand underground movement during an earthquake.
According to LADWP officials, the Foothill Trunk Line functions as a vital artery in the city’s water distribution system, transporting large volumes of water from major reservoirs and facilities to smaller mainlines serving local neighborhoods. City Councilwoman Monica Rodriguez noted that the completed project secures a critical investment in the San Fernando Valley, ensuring reliable service for local families and adequate water resources for first responders during a crisis.
Broader Infrastructure Modernization and Leak Rates
The Foothill Trunk Line initiative represents the largest and longest large-diameter earthquake-resistant ductile iron pipe installation in the nation, according to LADWP statements. City records show that LADWP has installed 67.2 miles of earthquake-resilient pipe across Los Angeles since 2012.
LADWP Interim General Manager David Hanson reported that the department has nearly tripled its annual mainline pipe replacement pace over a 20-year span to 240,000 feet per year, which includes more than 41,000 feet of earthquake-resilient pipe annually. Hanson stated that the agency’s water leak rate remains half the national average.
These ongoing improvements fall under the agency’s broader $8 billion, five-year Water System Capital Plan aimed at modernizing a municipal water system where many mainlines exceed 80 years in age. Mayor Bass and city council members continue to emphasize the capital improvement plan as a cornerstone for long-term water reliability and public safety across Los Angeles neighborhoods.
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